"I dived pretty deep into this character and it wasn't very pleasant one and so kept her distance from me...," Aaron adds. "She was very pleased when I left."

Taylor-Johnson's nightmare began three months before he started shooting when he decided to study psychopaths and serial killers like Jeffrey Dahmer and Ted Bundy to get into character.

"It was very disturbing and the process was pretty grueling," he explains. "Accumulating that kind of very dark knowledge wasn't very nice at all... I watched documentaries and tried to pick up mannerisms."

The movie, which also features Isla Fisher, Amy Adams, and Jake Gyllenhaal, has opened to glowing reviews in parts of Europe. It opens on 18 November (16).